Recoil check and barrel accelerator for a machine gun



S. G. GREEN Aug. 30, 1938.

`RECOIL CHECK AND BARREL ACCELERATOR FOR A MACHINE GUN Filed Aug. 25, 1937 Inv anim Samuel E ErEETL yM/Wff//M .dm w 2 22 7 4 m 4 3 M Q M n L, l)THW/ M 1 Qi/M n 6 5||| Attnr'T-LE Patented Aug. 30, 1938 BECOIL CHECK AND BARREL ACCELERATOR FOR A MACHINE GUN Samuel G. Green, Gray, Ga. Appucsnonnugust 23, 1931, serial No. 160,465

3 Claims.

(Cl. 89-l4) (Granted under the act ot March 3, 1883, as amended April 30, 1928: 370 O. G. 757) The invention described herein may be manufactured and used by `or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This .invention relates to a recoil check and barrel accelerator for a machine gun.

The purpose of the invention is to provide a recoil check and barrel accelerator which is especialiy adapted for the type of barrel mounting shown in my Patent No. 2,026,528 of January 7, 1936, and `involves an arrangement of a baille with respect to the barrel whereby the discharge of high pressure and high temperature gases is controlled by a restricted passage and so directed 15 as to prevent the accumulation of carbon and fouling of the bearing for the barrel.

To these and other ends, the invention consists in the construction, arrangement and combination of elements described hereinafter and.

.'0 pointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in the accompanying drawing, wherem:

Fig. 1 is a longitudinal sectional view of the iront of a machine gun constructed in accordance with the invention and showing the barrel in battery.

Fig. 2 is a similar fragmentary view showing the barrel in full recoil.

Fig. 3 is a detail view in side elevation of the gland and extension.

Fig. 4 is a sectional view on the line 4--4 of Fig. l.

l, Referring to the drawing by characters of reference there is shown the front portion of a machine gun comprising a barrel 5 which is disposed in a jacket 6 adapted to contain a cooling medium. A front end cap 'I on the jacket is I formed with a. xed cylindrical sleeve 8 having a reduced internal diameter at its inner end to provide a bearing-9 for supporting a movable sleeve I0. The sleeve I has a front inturned end II threaded to the muzzle of the gun barrel :I and serving to space the Abody of the sleeve from the barrel for the purpose of enabling the cooling medium to be in direct contact with the iront end of the barrel. In the normal "in battery position of the barrel its front end does not pron ject beyond the face of the end cap. The sleeve I0 however projects a slight distance beyond the cap and has a beveled face I2 to provide a flaring mouth.

A gland I3 disposed within and threaded to the ,-1 end cap 1 serves as a support or bearing for the iront part of the sleeve I0 and also contines a ring I4 which ls between the sleeve and bearing and holds a packing ring I against the front wall of the bearing 9. The gland includes a tu bular extension I6 having an internal diameter 5 greater than that of the gland so that it will be appreciably spaced from the projecting end of the sleeve I0. The inner portion of the extension I6 which is adjacent the end cap ls provided with a plurality of annularly arranged ports I1. 10 The outer portion of the extension is threaded internally for attachment of a plug or baille I8. The baille is formed with an axial bullet passage I9 having a flared entrance 20 which is spaced from the front face of the barrel. The rear part of the baille is conical, its apical portion 2| disposed within and spaced from the ilared mouth of the sleeve I0 to form a normally restricted gas passage 22 and its wall 23 meeting the extension on a line with the forward wall of the ports Il.

When a bullet ilred from the gun leaves the barrel and enters the baille the barrel has just started its recoil movement and has traveled to the rear about one-sixteenth of an inch. It is at 25 this stage that the high pressure and the high temperature gases immediately following the bullet impinge on the baille and react on the front face of the barrel to assist in driving the barrel rearwardly and thereby accelerate its movement and the resulting rate of re. At the same time the action of the gases on the baille tends to move the jacket 6 forwardly and counteract the forces of recoil exerted on the jacket and the mount (not shown). A portion of the high pressure and high temperature gases are vented through the ports I1, the restricted passage 22 between the bale and the sleeve insuring the maintenance of a suiclently high pressure to prevent the accumulation of carbon. The forcible discharge of the gases at this stage creates a vacuum on the outer side of the projecting end of the movable sleeve Ill-*and thereby prevents fouling of the bearing formed by the gland.

As the barrel continues on its recoil stroke of one and one-eighth inches the front edge of the sleeve recedes into the gland (Fig. 2), thereby enlarging the annular passage between the bale and sleeve and facilitating the discharge of the remaining low pressure gases from the barrel.

I claim:

1. In a machine gun, a jacket having a front end cap with a bearing, a gun barrel mounted for reciprocatlon in the jacket and normally having its muzzle within the end cap. a sleeve 55 on the barrel and supported in the bearing. the end oi' the sleeve projecting beyond the end cap and having a beveled face forming a flared mouth. a gland threaded in the cap and supporting the sleeve, a tubular extension on the gland spaced from the sleeve and having a plurality of ports in its inner end, a baule fixed in the outer end of the extension and having a conical inner end disposed within the dared mouth of the sleeve and spaced from the front of the barrel and the beveled face of the sleeve to provide a normally restricted gas passage, said bafe having a bullet passage with a flared entrance for reflecting gases onto the barrel.

2. In a machine gun, a jacket having a front end cap, a gun barrel mounted for reciproeation in the jacket, a sleeve fixed on the end of the barrel and slidably supported in the end cap,

said sleeve having a flared mouth normally projecting from the end cap when the barrel is in battery and movable into the end cap when the barrel is in recoiL'a supporting member fixed to the end cap in laterally spaced relation to the sleeve and having ports, and a bae carried by said member and having a conical inner end disposed within the ilared mouth of the sleeve and normally spaced a slight distance from the flared mouth of the sleeve to provide a normally restricted gas passage, said baiile having a bullet passage with a flared entrance for reiiecting gases onto the barrel. l

3. In a machine gun, a jacket 'havinga front end cap, a gun barrel mounted for reciprocation in the Jacket, a sleeve xed on the end of the barrel and slidably supported in the end cap, saidksleeve having a ared mouth normally projecting from the end cap when the barrel is in battery and movable into the end cap when the barrel is in recoil, a supporting member xed to the end cap and having ports, and a baille carried by said member and having a bullet pe and an inner end shaped complementary to the flared mouth of the sleeve. said inner end disposed wlthin the flared mouth of thesleeve and cooperating therewith to form a normally restricted gas passage. 

